Sub-hourly precise point positioning accuracy analysis – case study for selected ASG-EUPOS stations

Precise Point Positioning (PPP) is still considered a new technique of GNSS measurements intensively developed in recent years. One of the main advantages of this method is the autonomous mode of measurement, requiring only one receiver, which ensures the high accuracy of the measured position. The accuracy, in some modes of measurement and processing, is similar to the results obtained with the use of Relative GNSS technique (RGNSS). The main disadvantages of PPP include the need to introduce a set of corrections, which in the RGNSS are reduced using differential equations and a relatively long time (about 20 min or more) needed for ambiguity resolution.The analysis conducted so far concerning the determination of the PPP accuracy focused mainly on the results obtained from long (daily) static observation. The results obtained from the sub-daily observation, less often analysed, involved longer time intervals (1–8 h). In this paper, time series of position components derived from sub-hourly (30 min) PPP solutions were analysed. The analysis was based on 30 days of observations performed at 8 ASG-EUPOS system stations. For processing the collected GNSS observations (in different variants) the NAvigation Package for Earth Orbiting Satellites (NAPEOS) software was chosen.If it will be assumed that standard deviation (SD) can be a good measure of the accuracy of the obtained results, the conducted analyzes prove that the sub-hourly PPP technique can provide accuracy in the order of 0.5 cm (SD below 0.5 cm) for the horizontal position components and 1 cm (SD below 1 cm) for the vertical position component. The above accuracy was obtained in the multi-station PPP approach (fixed ambiguity solution). In float ambiguity solution scenarios the standard deviation increases up to 1 cm for horizontal components and up to 2 cm for the vertical component. The periodicity, in the obtained position components time series, were analysed using the Lomb-Scargle periodogram. Spectral analysis showed clear periodicity in the obtained results (especially for GPS-only fixed and float solutions). For GPS or GPS/GLONASS processing strategies 73% of detected periodic signals correspond to a multiple of the orbital periods of the satellites.